Inspect in memory hsqldb while debugging

问题:

We're using hdsqldb in memory to run junit tests which operate against a database. The db is setup before running each test via a spring configuration. All works fine. Now when a tests fails it can be convinient to be able to inspect the values in the in memory database. Is this possible? If so how? Our url is:

jdbc.url=jdbc:hsqldb:mem:testdb;sql.enforce_strict_size=true

The database is destroyed after each tests. But when the debugger is running the database should also still be alive. I've tried connecting with the sqldb databaseManager. That works, but I don't see any tables or data. Any help is highly appreciated!

回答1:

HSQL is in memory, so when you say that you're connecting with SQLDB Database Manager, you're not - you are instead connecting to another database in the memory space of the SQLDB Database Manager, not the one in the memory space of the unit test. This is why the database in the SQLDB Database Manager is empty.

You can run HSQL as a server using org.hsqldb.Server as described here.

Although the org.hsqldb.Server class is typically used to start-up a seperate process, you could instantiate and configure it in your unit test, which should allow a remote process to connect and query the database.

Alternatively, you'll have to write some sort of dump functionality that is called from within your unit test as need be.

As an aside, using HSQL in unit tests is just proving your code works against HSQL, which is different to the actual database. This means you can get false positives and vice versa. The same thing can be achieved with a mocking API or better, save the database testing for some decent integration tests that works with the real database.

回答2:

In your unit test or in the @Before / setUp() method, you can add the following line to launch the HSQL Database Manager:

org.hsqldb.util.DatabaseManager.main(new String[] {
  "--url",  "jdbc:hsqldb:mem:testdb", "--noexit"
});

or for the improved Swing version

org.hsqldb.util.DatabaseManagerSwing.main(new String[] {
  "--url",  "jdbc:hsqldb:mem:testdb", "--noexit"
});

The DB manager lets you inspect your schema and run SQL queries on the live in-memory database while the application is running.

Make sure to set a beakpoint or pause the execution one way or another if you want to check the state of your database at a specific line.

回答3:

Run your unit test to a breakpoint, then in the Debug perspective of Eclipse, open the Display view (Window, Show View, Display) and enter

    org.hsqldb.util.DatabaseManagerSwing.main(new String[] {
  "--url",  "jdbc:hsqldb:mem:testdb", "--noexit"
});

(as per dimdm's post), highlight it, right-click and choose Execute.

回答4:

You could also use the DatabaseManagerSwing class included in [HSQLDB][1] passing to it an open connection, that allows you to see the state of the database in the transaction the connection is in.

DatabaseManagerSwing manager = new DatabaseManagerSwing();
manager.main();
manager.connect(connection);
manager.start();